Bellingham WA Home Inspector: (King of the House): Chimney Flashings

A masonry chimney on the roof almost always has, or should have at least, a metal flashing around it. This is usually described in four sections. At the top, behind the chimney, is the head flashing. At the front, low side, is the apron flashing. Probably the most critical flashings are the step flashing and the counter flashing. These are at the sides and the step flashing is tucked under the shingles and runs up beside the chimney. The counter flashing is embedded into the mortar - or so we hope - and it routes water down over the step flashing. If water gets behind the step flashing, that is not good. A common problem comes in after a new roof has been installed. The roofers know how to do the roof but do not want to monkey with the old counter flashing, it being embedded in the mortar. So often they just pull it out, put in a new step flashing and then try to shove it back in place. Other times they tar it all together. The tar lasts about 20 minutes. This normally leads to a gap that would allow wind blown rain in around the step flashing. The photo below gives you a pretty good idea of the potential water intrusion area. The best way to fix this is to remove the old counter flashing, which is often rusted anyway, and embed a new one in the chimney mortar.

Thank you for stopping by.

Steven L. Smith

www.kingofthehouse.com